Carburetor



Sept. 4, 1934. D, FIRTH 1,972,734

CARBURETOR Original Filed July 20, 1927 2 Sheets-Sheet 1 Sept. 4, 1934.R H 1,972,734

CARBURETOR Original Filed July 20, 1927 2 Sheets-Sheet 2 Patented Sept.4, 1934 UNITED STATES David Firth,

Carburetor Company, tion of Indiana CABBURETOR Flint, Mich, assignor toMarvel Flint, Mich, a corpora- Application July 20, 1927, Serial No.207,137 Renewed May .17, 1934 Claims. (Cl. 261-34) This inventionrelatesto certain new and useful improvements in carburetors and moreparticularly to means for supplying an additional amount of fuel to themixing chamber of the 5 carburetor when the throttle is opened so as toincrease the richness of the mixture for accelerat-ion and to providemeans for injecting an additional amount of fuel into the mixing chamberby working the throttle for starting the internal combustion engine towhich the carburetor is attached. v I a The primary object of theinvention is to give greater acceleration to the engine each time thethrottle is opened, by means of a plunger positively connected tocarburetor throttle forcing a surplus of fuel thru the nozzles, and asecond plunger associated with the first mentioned plunger, continuingto force fuel thru said nozzles after the first mentioned plunger hasceased to operate.

Another purpose of the invention is to feed an extra amount of fuel tothe engine intake while the engine is in operation after the throttle isopened, and to continue to doso over a more or less extended period, inorder to improve the acceleration of the engine, such auxiliary meansfirst discharging fuel thru one of the carburetor nozzles andimmediately afterwards thru both of said-nozzles.

A still-further object is to provide such an auxiliary chamber with anovel piston means actuated by the throttle mechanism, and designed tocontinue the feeding of an extra amount of fuel to the engine intake fora short time, even after the throttle mechanism has come to rest.

Another object of my invention is to provide means for metering the fueldelivered to the high speed-nozzle controlled by the piston forinjecting the fuel to said nozzle whereby the fuel delivered to the highspeed nozzle is restricteduntil the throttle is moved into substantiallyopen position. Another object of my invention is to provide means forrendering the auxiliary mechanism more orless'inactive during warmweather by providing means for by-passing the fuel from the auxiliarychamber to the fuel bowl of the carburetor.

With the foregoing objects outlined, and with other objects in viewwhich will appear as the description proceeds, my invention consists inthe novel features hereinafter set forth in de- 5 tail, illustrated inthe accompanying drawings,

and more particularly pointed out in the appended claims.

Referring to the drawings, 4 v Figure 1 is a) top plan view of a portionof a carburetor equipped with my improvements; Figure 2 is a side viewof the same, partly in vertical section; Figure 3 is a detail sectionalview of a portion of such carburetor, showing my control valve 'set forsummer operations;

Figure 4 is a similar view with valve set for winter working;

Figure, 5 is a view similar to Figure showing a modification;

Figure 6 is a side view of the modified constructions, partly invertical section; Figure 7 is a fragmentary vertical sectional view of aportion of the carburetorshown in Figures 5 and 6, and with the controlvalve set for summer working; and 1 Figure 8 is a similar view with thecontrol valve in winter position. In'the embodiment of my invention asillustrated in Figures 1 to 4, I have shown a carburetor of the Marveltype in which a high and. low speed nozzle are employed having a suctioncontrolled valve arranged over the higl: speed nozzle, 1 designating themain fuel chamber or a fuel bowl which is provided with a dischargeport2 controlled by a check valve 3 The latter permits the fuel to flowfrom the chamber to the auxiliary chamber, which will be laterdescribed, but prevents the fuel from flowing in the reverse direction.a

The port 2 leads into a conduit 4, closed by a removable plug 5 so thatwhen the plug is removed, access may be had to the check valve or to theport 2 or conduit 4.

the control 1, but

Fuel entering the-conduit travels through the passageway 6 into theauxiliary chamber 7.

As shown, this chamber is preferably integral with the chamber 1 and hasa cylindrical bore closed by a threaded cap 8. Movably mounted withinthe chamber 7 is a solid piston 9 having a stem 10 which is adapted toreciprocate through apacking 11 arranged in the cap 8.

Thethrottle mechanism of the carburetor is pivotally connected to thestem 10 by a link 12, which has its lower end pivotally connectedthereto by a -pin 13 so as to form a loose connection between thethrottle. mechanism and the stem or piston rod whereby the piston isfree to move up and down within the chamber. A supplemental annularpiston 14 surrounds the stem 10 and cooperates with the solid piston 9.The supplemental piston has an air passage 15 through the same and thispassage is controlled by a check valve 16 which is carried by thesupplemental piston within a suitable housing preferably formed integralwith the piston as clearly shown and is adapted to be closed by theliquid in the auxiliary chamber when the supplemental piston movesdownwardly and to open under atmospheric pressure when the supplementalpiston is lifted upwardly by the solid piston 9.

A vent port-17 is placed in the upper end of the two chambers incommunication whereby air pressure in both chambers is equalized.

An extension 18 at the lower end of the carburetor is provided with apassageway 19 having internal threads 20 at its upper end to engage theexternal threads of a nipple 21 forming an economizing jet through whichextends a valve 22 carried by valve stem 23 that depends from the lowerend of the piston 9 so as to.

form metering means for metering the fuel supplied to the high speednozzle.

Fuel in the auxiliary chamber may always readily flow withoutrestriction through a conduit 24 into the main nozzle 25 of thecarburetor and a predetermined amount of fuel will flow to the highspeed nozzle 26 and whenever the piston 9 is in its lower position, fuelto the full capacity will fiow through the jet 21 and passage 19 to thehigh speed nozzle 26.

It will be seen by this construction that when the throttle lever is inthe position shown in Figure 2, the fuel-supplied to the high speednozzle is metered and as the piston moves downwardly so as to move thevalve out of the jet, the stem of thevalve being of less diameter thanthe valve itself, an additional'amount of fuel is supplied or allowed toflow to the high speed nozzle and as the two pistons cooperate with thechamber so as to force fuel out of the same,

when the throttle is moved into open position so as to cause the pistonsto descend, fuel will be injected through these nozzles and willcontinue to flow.

By the construction thus far described, it will be seen that I haveprovided means for accelerating the internal combustion engine to whicha carburetor constructed in accordance with my invention is attached,said means being of a novel construction and including two pistons whichcause the fuel to be injected for a predetermined length of time afterthe throttle has been moved into open position.

This construction also provides novel means for facilitating thestarting of the engine.

In the operation of my device, let us assume that the parts are in theposition shown in Figure 2 and that the throttle is closed. As soon thenas the throttle is moved into open position, the link 12 will cause thepiston 9 to rapidly move downwardly and this will cause fuel to beinjected from the nozzle 25 for at this time the valve 22 meters thefuel delivered to the high speed nozzle and the only escape of the fuelfrom the chamber is through the nozzle 25.

It, of course, being understood that a very smallamount might be forcedunder pressure past the valve 22. As soon, however, as the pistondescends sufficiently to open the valve 22, fuel will be forced from thenozzle 26 to the full capacity of the nozzle and as these are alloperated automatically by the movement of the throttle, I am able toinject at the proper time the proper amount of fuel to form thecombustible mixture which'will increase the acceleration of the internalcombustion engine to which my improved carburetor is attached.

As the piston 9 moves downwardly, the supplemental piston 14 will followthe same by gravity but at a slower speed and as the check valve 16 isclosed, the supplemental piston will continue to force fuel through thenozzles 25 and 26 for a short period of time, even after the throttlehas been moved to full open position.

It will be obvious that this extra supply of fuel to the intake of theengine will greatly facilitate the acceleration of the engine so as tosupply an additional amount of fuel when most needed.

Should the throttle 'be kept open even after the pistons 9 and 14 havereached their lowermost positions, the fuel will be drawn through thenozzles 25 and 26 by the suction exerted in the intake of the engine soas to operate in the ordinary manner.

When the throttle valve is moved towards closed position, the piston 9is moved upwardly and will carry along the supplemental piston 14 and atthis time the check valve 16 will automatically open so that the airvalve will travel downwardly through the passageway 15 into lowerposition in the chamber '7 and thus prevent any undue suction due to theraising of the piston.

As it may not be necessary or desirable to use my auxiliary means duringwarm weather so as to prevent the same amount of fuel being injected inwarm weather as in cold weather, I have provided the carburetor with aby pass means which during the summer will simply feed the fuel from theauxiliary chamber back into the main chamber when the piston is moveddownwardly so that only a small amount of fuel will be injected throughthe nozzles 25 and 26 as the throttle is moved into open position and itis, of course, understood that the calibration of the by pass in respectto the calibration of the intake to the chamber will control the amountof fuel injected. This by-pass means comprises ports 27 and 28communicating with a control valve chamber 29. The control valve 30 inthis chamber has a passageway 31 which when it registers with the ports27 and 28 (see Figure 3) permits the liquid fuel to flow from chamber '7to chamber 1 when the pistons move downwardly so that the greaterportion of fuel which ordinarily would be injected through the nozzlesof the carburetor is forced back into the float chamber of thecarburetor.

When the valve 30 is turned to the position shown in Figure 4, that is,to a point where the port 31 no longer registers with the ports 27 and28, then all travel of the fuel from chamber 1 to the chamber 7 must beby way of port 2.

To permit ready control of the device, the valve 30 is provided with ahandle 32, which may be manually moved by 'the operator to register witha summer indication 33, or a winter indication 34on the cover of thechamber 1.

In the modification of the invention as illusc it " All passageway 21:.into the auxiliary chamber and this passageway has a check valve 3a toprevent the reversal of flow of fuel.

A by-pass 27a.-28a places two points of the passageway 2a at oppositesides of the check valve in communication and this by-pass may be closedby a control valve 30a. The latter has a port 31a for placing the twoparts of the bypass in communication.

In Figure 7 the by-pass valve is shown in open position and in Figure 8it is inclosed position and in this form of the invention, the upperportion of the auxiliary chamber is alwaysin direct communication withthe atmosphere through a conduit 17a arranged in the piston rod 10a.

This embodiment of the invention operates similar to the constructionshown in Figures 1 to 4 inclusive and, of course, when the control valve30a is set for winter operation and the pistons 9a and 14a are depressedby the throttle mechanism, fuel will be forced to the low and high speednozzles 25a and 26a. 4

Obviously, when the handle 32a is set for summer operation, the valve300. is open and any liquid forced by the pistons, simply travelsthrough the by-pass 27a-28a back to the main fuel chamber.

While I have disclosed embodiments of the invention which have beenfound practical in commercial operation, I am aware that various changesmay be made in the details disclosed without departing from the spiritof the invention as expressed in the claims.

From the foregoing description it will be seen that I have provided acarburetor which, while not limited to the type of carburetor employinga high and low speed nozzle, is especially adapted to be used inconnection with this type of carburetor whereby the injecting meanscooperates with an econommg device so that fuel is not injected from thehigh speed'nozzle until the throttle has moved a predetermined distanceinto open position. I

It is, of course, understood that myimproved construction of pistonmeansfor injecting the fuel operates to carry out the idea of causingthe fuel to be injected for a predetermined length of time after thethrottle has been opened, will operate in connection with a carburetorhaving a single nozzle or any number of nozzles and therefore I do notwish to limit myself to any particular type of carburetor to which myimproved construction of injecting means is to be used, as Iarii'aware'that many changes can be made without departing from thespirit of my invention.

What I claim is:-

1. In a carburetor adapted to be used with an internal combustion enginehaving a throttle valve, a nozzle, means for furnishing fuel to saidnozzle, a chamber interposed in said means and adapted to contain arelatively small charge of fuel, a check valve permitting the now offuel into the chamber, but preventing reverse flow of the fuel, a valvecontrolled passageway by-passing the check valve, means in said chamberactuated by the throttle valve for forcing fuel from the chamber to saidnozzle, said means being constructed to continue the forcing of fuelafter the throttle valve comes to rest.

2. In a carburetor adapted to be used with an internal combustion enginehaving a throttle,

an auxiliary fuel feeding chamber, a throttle actuated piston forforcing fuel from the direction for forcing fuel from the chamber,

independently of the first mentioned piston.

3. In a carburetor, an auxiliary fuel feeding chamber, a piston rod inthe chamber, a main piston on said rod, a supplemental pistonsurrounding the rod, and a check valve associated with the supplementalpiston and adapted to close under fluid pressure when the supplementalpiston moves in one direction.

4. The combination with a carburetor having a mixing chamber, with athrottle valve controlling the outlet thereof, of a high and low speednozzle arranged to deliver fuel .into said mixing chamber, a main fuelchamber, an auxil-- iary fuel chamber, said auxiliary chamber being incommunication with the main chamber and said nozzles, a compound pistonmovably mounted in said auxiliary chamber for injecting fuel throughsaid nozzles, and means controlled by the movement of said compoundpiston for metering the fuel passing through said high speed nozzle,

r 5. In a device for feeding fuel to an internal combustion engine, athrottle valve, fuel nozzles, a piston for forcing fuel to said nozzles,an auxiliary piston associated with the first mentioned piston andfunctioning to continue to force fuel to the nozzles for a short timeafter the first mentioned piston has ceased its operation and meansassociated with said'flrst mentioned piston for metering the supply offuel to one of said nozzles, said means being adapted to increase thesupply of fuel through said noz-' zle as the throttle valve is moved toopen position.

6. In a carburetor adapted to be used with an internal combustion enginehaving a .fuel bowl, a throttle valve and a nozzle, means for feedingfuel to said nozzle from said fuel bowl, a chamber interposed in saidmeans, means actuated by said throttle valve for forcing fuel from saidchamber through said nozzle, 'said chamber being in communication withsaid bowl through an auxiliary passage and a valve in said passage forcontrolling the passage" of fuel therethrough for regulating the amountof fuel forced through said nozzle.

'7. In a device for feeding fuel to an internal combustion engine havinga throttle valve for controlling the passage of fuel to said engine, aplurality of fuel nozzles for progressively feeding 'fuel, a piston forforcing fuel to said noz--' zles, an auxiliary piston associated withthe first mentioned piston and functioning to continue to force fuel tosaid nozzles for a short time after the first mentioned piston hasceased its operation, and means foroperating said piston by the movementof the throttle valve.

8. In a device. for feeding fuel to an internal combustion engine, athrottle valve, a plurality of nozzles for progressively feeding fuel, apiston for forcing fuel through said nozzles, an auxiliary pistonassociated with the first mentioned piston and functioning to continueto force fuel to the nozzles foria short time after the first mentionedpiston has ceased its operation and means associated with the firstmentioned piston for metering the supply of fuel to one of said nozzles;

9. A carburetor having a carbureting passage,

under compression for injecting fuel through said nozzles into saidcarbureting passage and means operated by the movement of the throttlevalve for metering the fuel injected to one of said nozzles.

10. A carburetor having a carbureting passage, a plurality of fuelnozzles for delivering fuel into "said passage, a suction operated valvedisposed over one of said nozzles, a throttle valve for controlling theoutlet of said car bureting passage, a constant level reservoir, apiston for forcing fuel through said nozzles, an auxiliary pistonassociated with the first mentioned piston and functioning to continueto force fuel to said nozzles for a short time after the first mentionedpiston ceases its operation, means for operating said piston by themove' ment of the throttle and means associated with said piston formetering the supply of fuel to one of said nozzles. 1

11. A carburetor having a carbureting passage with fuel nozzles disposedtherein, one of said nozzles terminating in a plane above the othernozzle, a suction controlled valve arranged over the last mentionednozzle, a constant level reservoir for feeding fuel to said nozzles, apiston for forcing fuel through said nozzles, a throttle valve, meansoperated by the movement of the throttle valve for actuating saidpiston, and an auxiliary piston associated with the first mentionedpiston and functioning to continue to force fuel through said 'nozzlesfor a short time after the first mentioned piston has ceased itsoperation.

12. A carburetor having a carbureting passage with fuel nozzles disposedtherein, one of said nozzles terminating in a planeabove the othernozzle, a suction controlled valve arranged over the last mentionednozzle, a constant level reservoir for feeding fuel to said nozzles, apiston for forcing fuel through said nozzles, a throttle valve, meansoperated by the movement of the throttle valve for actuating saidpiston, an auxiliary piston associated with .the first mentioned pistonand functioning to continue to force fuel through said nozzles for ashort time after the first mentioned piston has ceased its operation,and means associated with the-first mentioned piston for metering thesupply of fuel to said nozzles.

13. A carburetor having a carbureting passage, 21. throttle valvemounted therein, high and low speed nozzles disposed in said carburetingpassage, a constant level reservoir for constantly supplying fuel tosaid nozzles, a suction operated valve arranged over the high speednozzle, a piston for injecting fuel through said nozzles, an auxiliarypiston associated with the first mentioned piston and functioning tocontinue to force fuel through said nozzles, for a short time after thefirst mentioned piston has ceased tle valve, a mixing chamber, high andlow speed nozzles delivering fuel to said chamber, a main fuel chamber,an auxiliary chamber in communication with said main fuel chamber andsaid nozzles, a compound piston Working in said auxiliary chamber, aconnection between said compound piston and the throttle valve of thecarburetor, and means operated by said compound piston for metering thefuel supplied to one of said nozzles.

15. In a device for feeding fuel to an internal combustion engine havingthrottle mechanism, a fuel nozzle, a-piston actuated by the throttlemechanism of the engine for forcing fuel through said nozzle, anauxiliary piston associated with the first mentioned piston andfunctioning to continue to force fuel tqthe nozzle for a short timeafter the first mentioned piston has ceased its operation and meansoperated by said piston for metering the fuel delivered to said nozzle.

16. In a device for feeding fuel to internal combustion engines havingthrottle mechanism, a nozzle, a piston rod having a main piston fixedthereon actuated by the throttle mechanism of the engine for forcingfuel to said nozzle, and a gravity actuated supplemental piston looselymounted on said piston rod above said fixed piston for continuing theforcing of fuel to the nozzle for a shorttime after the first mentionedpiston has come to rest.

17. In a-carburetor, a nozzle and a main fuel chamber, a throttle, anauxiliary chamber communicating with the nozzle and the main fuelchamber, a check valve in the line of communication between saidchambers to permit the flow of fuel from the main chamber to theauxiliary chamber, but preventing reverse flow of the fuel, a by-passplacing said chambers in communication, a manually operated controlvalve for said by-pass, and a compound piston composed of two pistons,one movable relative to the other actuated by said throttle for forcingthe fuel from the auxiliary chamber to said said piston and normallyurged toward the same,

said piston being so formed that the pumping operation of said pistondischarges a portion of the fuel above the piston and beneath the saidelement, said element thereby serving to return the fuel so dischargedafter the cessation of the pumping motion of said piston to prolong thedischarge period of said accelerating device.

20. In a device for feeding fuel to an internal combustion engine, afuel nozzle, a piston for forcing fuel to said nozzle, a gravityactuated supplemental piston carried by the first men--.

tioned piston, said pistons being movably mounted in respect to oneanother, said gravity actuated piston being raised by the firstmentioned piston and allowed to drop by gravity to continue to forcefuel to the nozzle for a short time after the first mentioned pistoncomes to rest.

21. In a device for feeding fuel to an internal combustion engine havingthrottle mechanism, a nozzle, a piston rod actuated by the throttlemechanism of the engine provided with a piston for forcing fuel to saidnozzle, a gravity actuated supplemental piston carried by the firstmentioned piston, said pistons being movably mounted in respect to oneanother, said gravity actuated piston being adapted to continue to forcefuel to the nozzle for a short time after the first mentioned pistoncomes to rest.

22. In a carburetor adapted to be used with internal combustion engineshaving a throttle valve, a nozzle, a constant level reservoir, a fuelpassage for furnishing fuel to said nozzle from said reservoir, achamber interposed in said fuelpassage adapted to contain a relativelysmall amount of fuel, a check valve permitting the flow of fuel intosaid chamber but preventing a reverse flow of fuel, a piston in saidchamber for forcing fuel to said nozzle, a gravity actuated supplementalpiston associated with the first mentioned piston, said pistons beingmovably mounted in respect to one another, said gravity actuated pistonbeing raised by contact with the first mentioned piston and allowed todrop by gravity to continue to force fuel to said nozzle for a shorttime after the first mentioned piston comes to rest.

23. In a carburetor for supplying a combustible mixture to an internalcombustion engine, a throttle mechanism for controlling the flow ofmixture to the engine, a nozzle, a fuel supply chamber and a passageleading therefrom 'to said nozzle providing a normal supply of fuel, anauxiliary fuel supply chamber, a main piston in said auxiliary chamberhaving a connection with said throttle mechanism and moving in responseto an opening movement of said throttle to force an additional supply offuel to said nozzle, a gravity actuated supplemental pistonin saidauxiliary chamber coaxial with said main piston and movable relativethereto, said pistons hav ing a direct engagement whereby thesupplemental piston is raised and held in potential position by the mainpiston when the throttle is closed and released when the main pistonmoves to discharge fuel from the chamber to the nozzle during an openingmovement of the throttle, said supplemental piston dropping by gravityafter release to continue to force an additional supply of fuel to saidnozzle for a short period after said main piston has come to 0 rest. I

24. In a carburetor for supplying a combustiblemixture to an internalcombustion engine, a throttle mechanism controlling the flow of combustible mixture to the engine, a nozzle, a float chamber and a passageadapted to provide -a. normal supply of fuel to said nozzle, a mainiston responsive to an opening movement of said throttle to force anadditional supply of fuel to said nozzle, and a supplemental pistonactuated by gravity and operativelyv associated with said main piston tobe raised thereby to potential position when the-throttleis closed, saidsupplemental piston being released by a discharge movement of said mainpiston and operating to continue to force an additional supply of fuelto said nozzle for a period after the main piston comes to rest.

25. In a carburetor for supplying a combustible mixture to an internalcombustion engine,

a throttle mechanism for controlling the flow of mixture to the engine,a nozzle, a fuel supply chamber and a passage leading therefrom to saidnozzle adapted to provide a normal supply of fuel, an auxiliary fuelsupply chamber, and a compound piston operating in said auxiliarychamber comprising a main portion having a mechanical connection withsaid throttle mech anism and moved positively in response to an

